create table sys_logs (slog_id    number(15), 
                       constraint sys_logs_pk primary key(slog_id), 
                       message varchar2(4000), 
                       navi_date date default sysdate);
                       
create sequence slog_seq;

create or replace procedure log_message(i_message in varchar) is 
  pragma autonomous_transaction;
begin
  insert into sys_logs (slog_id, message, navi_date)
  values (slog_seq.nextval, substr(i_message, 1, 4000), sysdate);
  
  commit;
end;
